Some 28,000 people have been evacuated from near the Russian city of Izhevsk where a fire broke out late yesterday at an arms depot housing artillery shells and rockets.
At least 45 people were injured and hundreds of homes are reported to have been damaged in the overnight fire.
Shells detonated by the fire caused windows as far away as 10km (6 miles) to shatter.
The arms depot is in the Udmurtia region of the western Urals, 900km (560 miles) east of Moscow.
It stores artillery shells, rocket-propelled missiles and old ammunition.
Some reports suggest the blaze may have been sparked by a discarded cigarette.
The fire has interrupted the flow of oil along a nearby pipeline.
Emergency teams have flown from the Russian capital to the scene where firefighters are battling the blaze.
Balls of fire rose from the depot, according to eyewitness accounts.
Two elderly people living near the depot have died of heart attacks caused by stress from the explosions, regional health minister Vladimir Muzlov said.
This is the second time in a week that a Russian ammunition dump has exploded.
An arms depot caught fire in the Russian region of Bashkiria at the end of May.
